Sulfuric Acid → 1-(4-Methyl-3-cyclohexen-1-yl)cyclopentan-1-ol

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Reaction Steps

To a stirred suspension of 46.8 g of magnesium in 250 ml of tetrahydrofuran was added 182 g of 1,4-dibromobutane in 700 ml of dry tetrahydrofuran over 1 hour. The gently refluxing reaction mixture was maintained at reflux for 2 more hours and then cooled to room temperature. A solution of 100 g of the methyl ester of 4-methyl-3-cyclohexene-1-carboxylic acid in 20 ml of dry tetrahydrofuran was added at 20°-30° C. with cooling by an ice bath. The reaction mixture was stirred at room temperature for 2 days, and the excess Grignard reagent was decomposed by careful addition of dilute sulfuric acid. Most of the tetrahydrofuran was evaporated, and the reaction product was extracted with ether. The ether phase was washed successively with water and saturated NaCl solution, dried with MgSO4, and stripped to give 120 g of crude product as an oil. Multiple redistillation of the oil gave 32 g of product b.p. 90°-92° C. (0.5 mm).

Provenance & Evidence